PhD Thesis Proposal Defence


"RWA and Wavelength Conversion in Wavelength-Routed All-Optical WDM
Networks"

By

Mr. Xiaowen Chu


Abstract

Wavelength Division Multiplexing (WDM) is a promising technology to
utilize the huge bandwidth of optical fiber. Wavelength-routed
all-optical network is a suitable architecture to serve as the backbone of
wide-area networks and metropolitan-area networks by providing
lightpath services for communications. Blocking has been the key
performance index in the design of a wavelength-routed network. Existing
research demonstrates that an effective routing and wavelength assignment
(RWA) strategy and a proper wavelength converter placement
algorithm are the two primary vehicles for improving the blocking
performance. However, these two issues have largely been investigated
separately in that the existing RWA algorithms have seldom considered the
presence of wavelength conversion, while the wavelength converter
placement algorithms have largely assumed that a static routing and random
wavelength assignment algorithm is employed.
In this thesis proposal, we present some strong evidences that these two
issues need to be considered jointly. We first investigate the
wavelength converter placement problem for different RWA algorithms. Under
the fixed-alternate routing (FAR) algorithm, we propose a
heuristic algorithm called Minimum Blocking Probability First (MBPF) for
wavelength converter placement. Under the least-loaded routing
(LLR) algorithm, we propose another heuristic algorithm called Weighted
Maximum Segment Length (WMSL). From extensive simulation results, we
observe that the proposed algorithms not only outperform existing
wavelength converter placement algorithms by a large margin, but they also
can achieve almost the same performance comparing with full wavelength
conversion under the same RWA algorithm.
The second work I am proposing is to investigate the dynamic routing
algorithm in the presence of wavelength conversion. We show that
existing dynamic routing algorithms cannot utilize the fiber link
resources efficiently  in the presence of wavelength conversion. We then
propose a weighted least-congestion routing (WLCR) algorithm that
considers both the distribution of free wavelengths and the lengths of
each route jointly. The performance of WLCR algorithm is still under
investigation. Finally, I am proposing a sparse-partial wavelength
conversion architecture, which can save the number of wavelength
converters significantly. In this architecture, two problems will be
examined. The first one is the wavelength assignment problem, and the
second one is the converter placement problem.


Date:				Saturday, 15 March 2003

Time:				2:00p.m.-4:00p.m.

Venue:				Room 1511
				Lifts 27-28

Committee Members:		Dr. Bo Li (Supervisor)
				Dr. Mounir Hamdi (Chairman)
				Dr. Brahim Bensaou
				Prof. Chin-Tau Lea (ELEC)


**** ALL are Welcome ****